The present invention is directed to the field of radiopharmaceutical synthesis. More specifically, the present invention is directed to a radiation shield for a synthesis device.
Commercial PET production facilities are often set up solely for the production of 18F-FDG. However, as other radiotracers are developed and adopted, the production facilities will need to be able to produce these other radiotracers as well. The FASTlab® system, sold by GE Healthcare, Liege, BE, was designed from the start as a true multi-tracer platform so as to enable a given production facility to offer multiple radiotracers without requiring costly expansion of the production areas. The FAST1ab system comprises a synthesis unit which operates a single-use cassette removably mounted thereon. The spent cassette is removed after the synthesis run and replaced by a fresh cassette which may be likewise operated to perform a synthesis run. Cassettes may be tailored to produce a specific radiotracer, and the synthesis unit is programmed to operate each different type of cassette to synthesize its particular tracer.
Oftentimes several FASTlab FDG syntheses are performed by a PET center on any one day. FASTlab FDG synthesis refers to the process of producing FDG labeled with a radioisotope, including but not limited to 18F or 11O, using an FDG-cassette mated to a FASTlab synthesizer. Multiple syntheses may thus be performed serially on a single synthesizer or performed using multiple synthesizers. This allows the PET center to send out multiple doses so that the patients can be scanned throughout the day and/or at different locations. It is theoretically possible to scan from a single run as much as 10 hours later for 18F-FDG, though one would probably have to use the entire batch as about 97% of the radiotracer would have decayed by then. Therefore it is much better to produce a new batch a few hours later.
Given the clinical needs to synthesize multiple radiotracers it is therefore likely that such facilities will need access to the hot cell soon after the end of one synthesis run, in order to start the synthesis run of a separate tracer. Residual activity in the cassette after a synthesis poses an exposure hazard to the operator who is replacing a spent cassette with a new one. Thus the operator is at risk of exposure to the residual activity occurs after synthesis when the operator transfers the spent cassette to a shielded disposal container. Access by an operator to the hot cells (ie, the production chambers where radioactive products are synthesized) to transfer the spent cassette will thus be restricted until the residual activity on the spent cassette below an established limit. While the FASTlab runs a rinse stage after the synthesis procedure which is designed to optimize the removal of such residual activity, given the scarcity of reagents available at this stage in the synthesis, it may be difficult to get the activity down to the levels quoted for FDG in the target product profile (<0.5% of start activity within 30 minutes from end of process), which is generally viewed as an ‘acceptable’ level of residual activity.
For instance, the present production of Fluciclatide using FASTlab leaves around 5% of the starting activity on the MCX cartridge of the cassette after the synthesis run (but prior to the rinse stage). If the synthesis is performed on a 37 GBq scale and the level of activity on the MCX cartridge can be reduced to 2.5%, however this still equates to around 433 MBq after 2 hours decay or 1678 μSv/hour at 20 cm distance. Running two back-to-back syntheses runs in quick succession (i.e., on two different cassettes), is thus technically difficult due to the residual dose to which the operator would be exposed during spent-cassette dismounting procedures. This requires more time before an operator may remove the spent cassette and then load a fresh new cassette onto the synthesizer. There is therefore a need for means to reduce operator exposure to latent radiation on a spent cassette so to better enable faster turn-around for mounting a new cassette to a synthesis device.
In view of the needs of the art, the present invention provides a collar specific for a separations cartridge used on synthesis cassette that can shield the operator from residual activity on the cartridge during the short time required for the dismounting procedure. For example, the radiation-shielding collar that may be sized to fit over a solid phase extraction cartridge on a FAST1ab® cassette and thus provide significant shielding of the operator from the extraneous dose. A 1 cm thickness lead collar will reduce the dose by around 80% (347 μSv/hr for the case above), or by almost 96% (72 μSv/hr) for a 2 cm collar, and could easily be re-used once the activity has dropped to near background levels. The present invention may alternatively be formed from tungsten. Tungsten collars are relatively more effective at shielding and may be more appropriate in the tight space present. Desirably, the shielding collar is non-disposable, in that it may be removed from a cassette once the activity has decayed to near zero, or a safe level after a synthesis run and placed on a fresh cassette prior to its mounting to the synthesis device.
The shielding collars of the present invention may be placed over the separations cartridge without requiring disconnection of the cartridge from either the cassette or its associated tubing. The present invention is thus able to maintain the GMP-condition of the provided cassette. Additionally, as the shielding collar of the present invention may be removed from one cassette and emplaced on another, the unit cost of the cassette need not be negatively affected and any shipping (e.g., transportation vibration, weight) issues provided by a mounted shielding collar may be obviated. As such the shielding collar of the present invention may be provided in a kit with a synthesis cassette which includes a separations cartridge used for the synthesis of a radiotracer. The shield collar is adaptable to disengageably engage the separations cartridge so as to shield an operator from residual activity remaining in the separations cartridge after a synthesis operation.
Commercially, many PET production facilities must be able to perform several back-to-back production runs of radiotracers. By introducing a shielding collar for the SPE cartridges, an operator may now replace the spent cassette sooner, as the effective dose to the operator will be limited by the collar, thus shortening the turn-around time for resuming tracer production using the synthesis device. Thus, even if a prior synthesis run results in significant levels of activity on the solid-phase extraction cartridge after the end of the synthesis, the present invention allows shorter down-time between synthesis runs.
Reference is now made to
Cassette 110 is attachable to a synthesis device, such as FASTlab, which cooperatively engages the cassette so as to be able to actuate each of the stopcocks and syringes to drive a source fluid with a radioisotope through the cassette for performance of a chemical synthesis process. Additionally, the synthesis device can provide heat to the reaction vessel of cassette 110 as required for chemical reactions. The synthesizer is programmed to operate pumps, syringes, valves, heating element, and controls the provision of nitrogen and application of vacuum to the cassette so as to direct the source fluid into mixing with the reagents, performing the chemical reactions, through the appropriate purification cartridges, and selectively pumping the output tracer and waste fluids into appropriate vial receptacles outside the cassette. The fluid collected in the output vial is typically input into another system for either purification and/or dispensement. After product dispensement, the internal components of cassette 110 are typically flushed to remove latent radioactivity from the cassette, although some activity will remain. Cassette 110 thus can be operated to perform a two-step radiosynthesis process. By incorporating SPE cartridges on the manifold, cassette 110 is further able to provide simple purification so as to obviate the need for HPLC.
Cassette 110 includes, a manifold 112 including twenty-five 3way/3position stopcocks valves 1-25, respectively. Manifold valves 1-25 are also referred to as their manifold positions 1-25 respectively, as more clearly shown in
A 14 cm length of a tubing 122 extends between the free end of cartridge 114 and the luer connector of manifold valve 17. An 8 cm length of tubing 124 extends between the free end of cartridge 116 and the luer connector of manifold valve 23. A 14 cm length of tubing 126 extends between the free end of cartridge 120 and the luer connector of manifold valve 20. Additionally, tubing 128 extends from the luer connector of manifold valve 1 to a target recovery vessel 129 (shown in
A tetrabutylammonium bicarbonate eluent vial 130 is positioned within the vial housing at manifold valve 2 and is to be impaled on the spike therein. An elongate 1 mL syringe pump 132 is positioned at manifold valve 3. Syringe pump 132 includes an elongate piston rod 134 which is reciprocally moveable by the synthesis device to draw and pump fluid through manifold 112 and the attached components. QMA cartridge 136 is supported on the luer connector of manifold valve 4 and is connected via a 14 cm length of silicone tubing 138 to the luer connector of manifold position 5. Cartridge 136 is desirably a QMA light carbonate cartridge sold by Waters, a division of Millipore. The tetrabutylammonium bicarbonate in an 80% acetonitrile; 20% water (v/v) solution provides elution of [18F]fluoride from QMA and phase transfer catalyst. A fluoride inlet reservoir 140 is supported at manifold valve 6.
Manifold valve 7 supports a tubing 142 at its luer connector which extends to a first port 144 of a reaction vessel 146. The luer connector of manifold valve 8 is connected via a 14 cm length of tubing 148 to a second port 150 of reaction vessel 146. The luer connector of manifold valve 9 is connected via a 42cm length of tubing 152 to a vial 154 containing a mixture of 40% MeCN and 60% water (v/v). The acetonitrile and water mixture is used to enable primary purification of Flutemetamolat the first SPE cartridge 114. The luer connector of manifold valve 10 is connected via a 42 cm length of tubing 156 to a vial 158 containing 100% MeCN used for conditioning of the cartridges and the elution of Flutemetamolfrom the first SPE cartridge 114. Manifold valve 11 supports a barrel wall for a 5 ml syringe pump 160. Syringe pump 160 includes an elongate piston rod 162 which is reciprocally moveable by the synthesis device so as to draw and pump fluid through manifold 112. The vial housing at manifold valve 12 receives vial 164 containing 6-ethoxymethoxy-2-(4′-(N-formyl-N-methyl)amino-3′-nitro)phenylbenzothiazole). The vial housing at manifold valve 13 receives a vial 166 containing 4M hydrochloric acid. The hydrochloric acid provides deprotection of the radiolabelled intermediate. The vial housing at manifold valve 14 receives a vial 168 of a methanol solution of sodium methoxide. The vial housing at manifold valve 15 receives an elongate hollow spike extension 170 which is positioned over the cannula at manifold valve 15 and provides an elongate water bag spike 170a at the free end thereof. Spike 170 pierces a cap 172 of a water bottle 174 containing water for both diluting and rinsing the fluid flowpaths of cassette 110. The vial housing at manifold valve 16 receives a vial 176 containing ethanol. Ethanol is used for the elution of the drug substance from the second SPE cartridge 116. The luer connector of manifold valve 17 is connected to a 14 cm length of silicone tubing 122 to SPE cartridge 114 at position 18. Manifold valve 24 supports the elongate barrel of a 5 ml syringe pump 180. Syringe pump 180 includes an elongate syringe rod 182 which is reciprocally moveable by the synthesis device to draw and pump fluid through manifold 112 and the attached components. The luer connector of manifold valve 25 is connected to a 42 cm length of a tubing 184 to a third port 186 of reactor vessel 146.
Cassette 110 is mated to an automated synthesizer having rotatable arms which engage each of the stopcocks of valves 1-25 and can position each in a desired orientation throughout cassette operation. The synthesizer also includes a pair of spigots, one of each of which insert into ports 121a and 123a of connectors 121 and 123 in fluid-tight connection. The two spigots respectively provide a source of nitrogen and/or a vacuum to manifold 112 so as to assist in fluid transfer therethrough and to operate cassette 110 in accordance with the present invention. The free ends of the syringe plungers are engaged by cooperating members from the synthesizer, which will then apply the reciprocating motion thereto within the syringes. A bottle 174 containing water is fitted to the synthesizer then pressed onto spike 170 to provide access to a fluid for driving compounds under operation of the various-included syringes. The reaction vessel will be placed within the reaction well of the synthesizer and the product collection vial and waste vial are connected. The synthesizer includes a radioisotope delivery conduit which extends from a source of the radioisotope, typically either vial or the output line from a cyclotron, to a delivery plunger. The delivery plunger is moveable by the synthesizer from a first raised position allowing the cassette to be attached to the synthesizer, to a second lowered position where the plunger is inserted into the housing at manifold valve 6. The plunger provides sealed engagement with the housing at manifold valve 6 so that the vacuum applied by the synthesizer to manifold 112 will draw the radioisotope through the radioisotope delivery conduit and into manifold 112 for processing. Additionally, prior to beginning the synthesis process, arms from the synthesizer will press the reagent vials onto the cannulas of manifold 112. The synthesis process may then commence.
With reference to
Similarly, now referring to
Given the localization of the residual activity in these cassettes, the present invention provides a shielding collar for the separations cartridge so as to shield an operator from the residual activity.
Collar body 212 is formed from a radiation-shielding material, such as lead, tungsten, or elkonite. Shield collar 210 is thus able to reduce an operator's exposure to the retained activity on the separation cartridge. While it is desirable that shield collar 210 sufficiently protect an operator so as to allow the operator to dismount the cassette from the synthesis unit immediately after the synthesis run, the present invention also contemplates that the protection provided by shield collar 210 allow the operator to dismount the cassette earlier than if no shielding were provided about the separation cartridge. Thus, for a given synthesis, an operator will not have to wait as long prior to dismounting the spent cassette than would be required without the present invention.
Referring now to
Components 410a and 410b may be individually placed about a separations cartridge and then held together thereabout to shield the residual activity within. The present invention contemplates that a third piece may be applied to hold the two components together, such as a conventional clip, a clamp or a plastic cable tie. Desirably, components 410a and 410b include the means for holding each other together, such as mating detents or other each support a substantially planar locking flange 450 and 460, respectively. As shown in
In operation, collar component 410a is positioned to one side of a separations cartridge so that the cartridge is positioned adjacent surface 426a. Then, collar component 410b is positioned on the opposite side of the cartridge as component 410a and higher above the manifold than component 410a. The two components are brought together such that tongue 462 and tooth 464 are inserted into channel 452 so that tongue 462 is held within channel 452 and flange 450 is positioned between tooth 464 and flange 450. Shielding collar 450 may thus be held about the separations cartridge during and after a synthesis run and provide shielding to an operator while removing the cartridge (i.e., on a cassette) from the synthesizer. Shield components 410a and 410b may then be removed from about the cartridge once the residual activity within the cartridge has decayed to a safe level.
Any of the shielding collars of the present invention are contemplated to be formed from only the shielding material. Alternatively, the present invention also contemplates that the shielding collars of the present invention may additionally include a coating or elastomeric cover on one or more its surfaces. The coating or cover may, for example, be provided on just the outer surface but is desirably provided on any surface which an operator may contact while manipulating the shield.
While the particular embodiment of the present invention has been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from the teachings of the invention. The matter set forth in the foregoing description and accompanying drawings is offered by way of illustration only and not as a limitation. The actual scope of the invention is intended to be defined in the following claims when viewed in their proper perspective based on the prior art.
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/US11/65307 | 12/16/2011 | WO | 00 | 6/14/2013 |
Number | Date | Country | |
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61424069 | Dec 2010 | US |